Method of and apparatus for drying including solvent recovery



` Dec. 8l 19255-` v n G. D. HARRIS METHOD OF' AND APPARATUS FOR DRYING INCLUDING SOLVENT RECOVERY I 'Filed May 6, 1921 Patented Dec. 8, l1925-.

UNITED STATES y Y 1,564,783 PATENT Y OFFICE.

GORDON DON HARRIS, OE I'sDIr, NEw Y ORx, AssIGNoR, BY'MESNE ASSIGNMENTS, To

TRE INDUSTRIAL DRYER CORPORATION, oEsTAMEoRD, v CONNECTICUT, A OOR- IoRATION OE CONNECTICUT.

METHOD l.AND -APPARATUS-:FOR DRYING INCLUDING SOLYENT RECOVERY.

Application filed May 6,

To all 'whom it may concern.'

Be it known that I, GORDON DON HARRIS, a citizen of the United States, residing at slip, county of Suffolk, and State of New York, have invented a certain new and useful Method of and Apparatus for Drying Including Solvent Recovery, of which the following is a specification. c

This invention pertains to the art of oxidizing and fdrying, and more .particularly to the recovery of solvents initially employedl in the material under treatment and evaporated from such material by the oxidizing or drying thereof, ywhereby the solvents are convents of one form or another,and that in oxidizing or drying such materials the solvents are volatilized and givenof iwith or 'without aqueous vapors, 'fromsuch mater1als. One object of this invention 1s to recover all, or substantially all, the solvents presentin or upon the surfaces of the material, and a further object is to conduct the oxidizing or drying of such material in a partial vacuum whereby the exchange of heat for the `solvent and aqueous content 'is carriedV on rapidly, efficiently and economically.

of supporting means within a closed chamber which constitutes a part of a circulatory path from which outside atmospheric air is' excluded during the drying and recovery periods. The circulation of an oxidizing atmosphere within this closed circulatory path is set up by a difference in temperature due to expanding such atmosphere by heating it within a vdefinite zone of said circulatory path and to condensing such atmosphere by contact with relatively cold surfaces of a condenser or condensers positioned within another Vdefinite -part of said circulatory path, as a result of which expanding and f condensing operations the atmosphere flows within said circulatory path including the chamber, and into contact with the material. The owing atmosphere carries heat to the material for driving Ofil the solvent and aqueous contentY thereof, such solvent content 1921. seriaINa. $7,493.

with or withoutimoist-ure being given o as a volatile vapor or gas whichis taken up by the drying atmosphere and is.carried from..

chambers being equipped with a condenser or condensers to which a coolingmedium of one character or .another issupplied for cool- 'ingthe surfaces-of such condensers to a desired degree, such as. to thedew point.4 The atmosphere carrying the volatile vapors,

ilows into contact with cold surfaces, and

thus such vapors are condensed and the atmosphere is chilled, provision being made for collecting such condensate and for dis-- charging the same from thecirculatory path. The condensate may be Vdistilled Or otherwise treated for the purpose of making the sol- Yvent available for re-use.

Other functions and advantages of the invention will appear from the following description taken in connection with the drawing, whereinvthe figure is a vertical section through an apparatus for carrying out my invention.

:The vhousing A '-is constructed with air tight walls, insulated in a well known mannel', to .thel end that no outside atmospheric air may be admitted during the periods of conducting the drying or oxidizing operation and the recovery of the solvent, such operations involving the utilization of a dry- The material is supported by any form ing or oxidizing atmosphereset into motion by a difference in temperature within a closedA circulatory path and -Without, resorting to means, such as blowers or exhausters, for

mechanically circulating such atmosphere.

lVithin the housing are' partitions a, in-

sulated' to, arrest the transmission throughwalls or partitions a are parallel to the sides of the housing, and form therewith side chambers C C vat opposite sides of the material chamber. The oor b is parallel to the bottom of the housing. so as to form steam or hot water, -is adapted to be supplied, l provision being made for controlling the flow;

of the heating medium to the coils for regu'-v lating the heating effect thereof upon the 5 j ports b a2 for indicating the temperatures `lof theheated atmosphere liowing into and out of chamber B.

drying or oxidizing atmosphere.

- Within the housing and above the roof a to the material chamber are inclined partitions c which extend across the side chambers C, said partit-ions c and roof a pro` ducing certain chambers F which co-mmuni` l. cate with material chamber B by way of port a2 and which chambers F have free communication with the side chambersC. Positioned within the chambers F are condensers G, herein shown as coils to which there is supplied an appropriate cooling medium, such as cold water or the usual refrigerating agent, provision being made for controlling at will the feed of 'the cooling medium to said condensers with a view to keeping the surfaces thereof at a low temperature, such as at the dew point. The condensers are inclined downwardly toward the sides of the housing and the'chambers C, and in the service of the apparatus such condensers perform the twofold functlon of condensing the volatile vapors and aqueous vapors present in the drying atmosphere flowingl within the chambers F and of chilling such atmosphere so that its temperature is mai terially reduced, to the end that the atmospliere flowing out of chamberB and within the chambers F will become chilled and descend within the-chambers F and C, and thence pass into expanding chamber D for contact with the heater E.- Chambers F constitute cooling chambers for the drying atmosphere, whereas chamber D is a heating chamber.

The chambers B, F, C, D constitute the closed circulatory path for the flow of the' drying or oxidizing atmosphere, whereof the material chamber B is intermediate the heating chamber D and the cooling chambers F, so that the drying or oxidizing atmosphere, carrying the volatilized solvent vapors and aqueous vapors out of material chamber B,

flows into contact with the cold surfaces of condensers G, thus chilling the atmosphere vand condensing its volatilized Solvent and aqueous content.

Provision is made for collecting the condensate which drips from the cold surfaces of the condenser. Below the inclined condensers are tanks H positioned within chambers C, each tank having a draw-off cockh' extending through the housing for discharging the condensate from the circulatory path. The condensate may be distilled or otherwise treated by a subsequent operation for tlxe separation of the water of condensation A'collecting 'gutters L .zas shown.

drip from the 'surfaces ofthe condenser and lodge upon the sloping'roof a ofchamber B, wherefrom the liquor is free to gravitate into leadingto the tanks H,

#Thermometers I I are positioned in the A thermometer I ispositioned inv the space b at the bottom of the chamber and in the path of the atmosphere flowing from heating chamber D into the material-containing chamber. Other wet-bulb thermometers (two or more as at I', J arey positioned at the upper part of the materialcontaining chamber and within the space a2 said web bulb thermometers I', J', being in the line of flow of the atmosphere flowing out of the material-containing chamber. Said thermometers I, J may be of any desired character 'known to the art for indiv eating the humidity of the atmosphere flowing out of the material chamber, but as such wet bulb thermometers are well known in the art, I have not considered it necessary to further illustrate or describe the same.

The material is supported by suitable means within the treating chamber B, but in the form shown, said supporting means con. sists of trays K arranged in two vertical series within saidvchambereach tray rest-` aqueous and volatile vapors emanating from 'the material in the trays results in a decrease ofthe temperature of the drying or oxidizing atmosphere, to compensate for which drop in temperature the atmosphere is reheated as it flows within the tortuous flow passage within said chamber B. Said reheaters O are shown as coils each positioned intermediate two adjacent trays, or between the top of one tray and the bottom of the next tray, and not at the ends of the trays, whereby the atmosphere flowing within the tortuous passage has repeated contacts with the material and with the reheaters for the purpose of heatingthe flowing atmosphere to a desired temperature, either to keep said atmosphere at a constant temperature, but preferably to heat it increasingly during its vLissy-7a3 flow from thebottoin'to the top of' cham#` atmosphere flows from chamber B into con.

densing tlues or chambers F.l This vent in the normal operation of the apparatus is closed by a valve p exposed to and closed by the pressure of external atmospheric air, but said vent tube is open at the lower part thereof for the free ingress of the atmosphere internally of the housing, so that the valve is exposed to the pressure of both the internal atmosphere and of the external atniospheric air, the preponderance ofthe latter normally tending to closetlie valve.

In operation, the material is introduced by trays or otherwise into chamber B, and the latter thereupon is closed for excluding outside atmospheric air during the drying or oxidizing period. Steam is admittedto heater E and reheaters O, Whereas a cooling` medium is supplie-d to condensers G G, the inlowof the `heating medium and of the cooling medium being regulated as required by the Working conditions Within the circulatory path constituted by chambers B, F, C, lD. The contact of the atmosphere with the cold surfaces of the condensers chills said atmosphere Within chambers F and results in the descent Within chambers C, whereas the heat units given oli' by-lieaters E expands the atmosphere for effecting its ascent within chamber B, the atmosphere being thus set into motion by the difference in temperature given to it at distinctly different zones in the circulatory path and the flow of such'diying or oxidizing atmosphere being established Without resorting to mechanical means for effecting such circulation. The direction of flow of the atmosphere Within chamber B is in ytortuous paths directed by the trays and the baffles, at which period the atmosphere exchanges heat for the aqueous and'solvent content vof the material, said atmosphere being boosted by the action of the relieaters positioned in the line of How Within the chamber, and the teinperature and humid condition of such atmos? phere at different stages of its How being indicated by the thermometers. As the atmosphere emerges from the top of chamber B carries the volatilizedsolvent and aqueous vapors given off by the material iiito'contact with the cold surfaces of the condensers, the. etiect of which is twofold, to condense the volatilized vapors and the aqueous vapors so that the condensate is collected by the gutters l1. and the tanks H,

and to chill the atmosphere, insuring the downward flow Within chambers F C, and thence to the primary heatei.

It will. be understood that a higher tenii the vent valve.

perature `Within the apparatus is established atthe beginning of the operation than is employed in the subsequentnormal operation, such initial higher temperature tending to expand the at-niosphere and to increase the pressure therein for initially opening temperature takes place and the. pressure Within the apparatus is less than the outside atmospheric air, and thereafter the condensers chill .some of the air present in theapparatus and such chilling with the reduction in temperature sets up a `flow of the atmosphere the pressure of which is normally less than that of the outside atinospheric air until in the cycle of repeated operations the internal pressure exceeds that of the outside atmospheric air, the result of which is that theinternal pressure opens the vent valve although at infrequent or irregular intervals.

The flow of the drying or oxidizing` atmosphere Within the circulatory path takes place Thereupon a reduction in.

at a pressure less than external atmospheric pressure (14.7), resulting in vent valve p being kept in a closed condition; butin continued operation the heat units given oit to the atmosphere by the heaters and reheaters so increases the volume of the oxidizingatmosphere that the pressure internally of the housing exceeds the external atmospheric pressure, whereupon the vent valve p is opened for such a length of time that-some of the atmosphere escapes through the vent or until its pressure is reduced below the outside atmospheric pressure, the vent valve p being thereupon closed. The

automatic opening of the ventvalve occurs a intermittently for the exit of 'a limited volumeof the drying atmosphere, attended by a consequent rarification of 1suc-li atmosphere, the effect of which-is to conduct the drying or oxidizing;` operation and the recovery ofsolvents in a partial vacuum and under conditions insuring the recovery of practically all the solvent material present in or upon the surfaces of the material under treatment.

Having thus fully' `described the invention, what I claim as new and desire to secure by Letters Patent is:

1. AIn the art of drying, the process which consists in placing the material to be treated Within a closed circulatory path fiom which outside atmospheric air is excluded and iwithiii which circulatory path is established part of the circulatory path, and chilling and condensing the. divided currents of the attenuated atmosphere within different parts otl said circulatory path and remote from the heating zone aforesaid.

2. In the art of drying, the process which consists in setting up an attenuated oxidiz- .ing atmospherewithin a closed circulatory at an upper part of said circulatory pathand within the same, and chilling the divided currents of the attenuated atmosphere by conducting said currents into contact Y separately with condensers positioned within the circulatory path at points remote from the heating zone and acting individually to condense the aqueous and volatile solvent vapors carried by said attenuated atmosphere.

3. In the art of drying, the process which consists in setting up an attenuated atmos- -phere within a closed circulatory path from which outside atmospheric air-is excluded and the pressure of which attenuated atmosphere is less than that of outside atmospheric air, heatingv at a definite point within said circulatory path the lattenuated atmosphere and so expanding the same to create an upward flow Within a part of said circulatory path, dividing the uplowing attenuated atmosphere at an upper portion of said circulatory path to establish separate currents in said flowing attenuated atmosphere, chilling the separate currents of said atmosphere by contact with condensers situated Within the circulatory path at points remote from the heating zone and condensing the aqueous and volatile content in said divided currents of said attenuated atmosphere, and collecting the condensate so as to discharge the same from the circulatory path.

4. In the, art of'drying, the process which consists in setting up an attenuated atmosphere within a closed circulatory path from which outside atmospheric air is excluded and the pressure of which attenuated atmosplieret is less than'that of said outsidel atmospheric air, alternately heating and chilling Vthe attenuated atmosphere at4 definite zones within the circulatory path and so expanding and contracting the said attenuated atmosphere so as to create an uplow and a downtlow within distinct areas of' the circulatory path, vdividing the upwardly liowing attenuated atmosphere at the top of the circulatory path to create individual eurrents of said atmosphere, conducting the attenuated atmosphere` during the uptiow thereof into contact with material to be dried, and reheating said uptlowing attenuated atmosphere in the periods between the e of said atmosphere by flowing the same into contact with cold surfaces of a condenser positioned within said circulatory path,'and venting said circulatory path at intervals by utilizing the pressure of the oxidizing atmosphere to open a valve normally closed by external atmospheric pressure.

6. In a drier, a housing provided with a material containing chamber forming part of a circulatory path within which is established an attenuated atmosphere and from which path outside atmospheric air is excluded, said chamber being provided inthe top thereof with a` substantially central outlet, a plurality of flues leading from said outlet and establishing paths for the downflow of separate currents of the attenuated atmosphere flowing through said outlet from said chamber, a plurality of condensers positioned within said'rflues and adjacent to said outlet from the chamber, and heating means adjacent an inlet to the bottom portion of said chamber. a

7. In a drier, a housing provided with a material containing chamber forming part of a circulatory path wit-hin which is established an attenuated atmosphere and from which which path outside atmospheric air is excluded, said chamber being provided in the top thereof with'a substantially central outlet, a plurality of tlues leading from said central outlet and establishing paths for the downtlow of separate currents of the attenuated atmosphere flowing through said outlet from said chamber. a plurality of condensers positioned within said tlues and adjacent to said' outlet from the chamber, means adjacent the condensers and within said liues for oscillating the coudensate produced by contact of the downflowing currents of the attenuated atmosphere with said condensers, and heating means within the circulatory path and adjacent an inlet to the bottom portion of said chamber.

8. In a drier, a housing provided with a material containing chamber forming part of a circulatory path within which is eslill) ltlf) -tablished an attenuated atmosphere and from which path outside atmospheric air is excluded, said chamber'Y being provided in the top thereof With a substantially central outlet, a plurality of flues leading from said outlet and establishing paths orthe down-` flow of separate currents of the attenuated condensing means positioned Within the atmosphere flowing through said outlet from said chamber, a plurality of condensers positioned Within said flues and adjacent to said outlet from the chamber, heating means positioned Within the circulatory path 7 adjacent to the inlet at the bottom portion'of the chamber, 'and boosters positioned Vwithin the chamber intermediate the inlet at the bot-V tomand the loutlet at the top of said chamber. v c

9; In a drier, a housing provided with a circulatory path including a 'material chamber and from which outside atmospheri ic air is excluded during the drying period,

circulatory path adjacent lthe exit from said the circulatory path for lWarming an atmosphere adapted to flow 'Within said path and for expanding the said atmosphere to a point at which the pressure within the housing is in excess of the external atmospheric pressure, means at the top portion of said material chamber for dividing the upflowing atmosphere, into separate currents emerging from the top portion of the chamber, yand a valved exit to said circulatory path, the valve of said exit being normally closed by external atmospheric 'pressure and fsaid valve being exposed to the pressure of the atmosphere Within the housing and adapted to be lopened when the pressure therein is in excess of the atmospheric pressure. f

chamber, heating means positioned Within A In testimony whereof I have hereto signed g myname this 29th day of April, 1921.

VGORDON DON HARRIS. 

